Asphalt cutback containing an aliphatic phosphoric acid ester



Patented Apr. 15, 1952 2,592,564 ICE I ASPHALT OUTBACK CONTAINING AN ALI- PHATIC PHOSPHORIC ACID ESTER Harley F. Hardman, Wicklifize, Ohio, assignor to The Standard Oil Company, Cleveland, Ohio, a

corporation of Ohio No Drawing. Application May 22, 1948, Serial No. 28,729

13 Claims. (Cl. 106--273) The present invention relates to an asphaltcontaining composition of improved wettin properties. More particularly, the invention relates to an asphalt mixture comprising asphalt in conjunction with an additive capable of imparting improved wetting properties to the asphalt, said additive consisting of an organic derivative of a pentavalent phosphoric acid, such as orthoor pyrophosphoric acids.

Many asphalts have good covering properties with respect to sand, rock, or other construction materials. However, when the solid aggregate becomes wet, either before or after coating, it often is impossible to obtain or retain a satisfactory bond between the asphalt and the stony material or other aggregate.

It is obvious that a good bonding property of the asphalt is of primary importance, and that this property has to be independent of the dry or moist state of the material to be covered as well as of the prevailing weather. It is, therefore, an object of the present invention to improve the bonding properties of asphalt and similar bituminous material by adding thereto an agent which will impart to the asphalt the necessary bonding capacity at all times and under all conditions. a

By the term asphalt as used hereinafter, is included natural asphalt, such as asphaltic rocks, tars and pitches obtained in the distillation of coal or wood, petroleum residues, cracking coil tars, etc. The invention is particularly adapted for use with asphalt from petroleum sources.

The asphalt used in accordance with the in vention may be any of the above materials, or a mixture thereof, with any solvent. When an asphalt is mixed with a solvent it is known as cut-back. An uncut asphalt is usually viscous, plastic, or even solid at ordinary temperatures. It is usually applied to a surface to be coated after the asphalt has been heated to soften it or liquefy it. Cut-back asphalt, such as the socalled medium curing (MC) type, is produced by fluxing the asphalt with a suitable solvent such as a naphtha or a similar hydrocarbon. It may be applied in the cold or at room temperature, except in cut-back asphalt having a small amount of solvent which may be warmed. There are six grades of the medium curing type of cut-back asphalt, known as MC-O, MC-l, MC-2, MC-S, MCI-4 and MC-5, containing dliierent amounts of solvent. MC- for instance, contains about 50% solvent and MC-5 contains about 18% sol,- vent. These various grades are used for applying to various surfaces, and in the case of road surfaces in the manner designated for the respective grades. MC-3 for example, is used as a binder in surface treatments, in road mix construction with open-graded or dense-graded aggregate, and in cold-patch mixtures in opengraded aggregate. The cut-back asphalts must be free from water and conform to certain ASTM" two general formulas:

requirements. (See for instance, ASTM 1944, pages 432433.) As illustrative of a typical cutback asphalt, the following is the analysis of the MC-3, which is described more particularly hereinafter:

Viscosity at 140 F., Saybolt Furol v 4.34 Specific gravity at 60 0.9548 IBP, "F 438 45% 50,0 74% 600 78.5% 680 Penetration at 77 F. (on residue) 171 Crude source-Illinois.

It has been found, in accordance with the in vention, that cutback asphalts having poor ad'- herence to aggregate can be very much improved in this respect by incorporating therewith an organic derivative of a pentavalent phosphoric acid such as orthoor pyrophosphoric acid (or their anhydride), the organic radical or radicals being derived from higher molecular weight hydroxy compounds of 10 or more carbon atoms which are linked to the phosphoric acid through their hydroxy group. Among the compounds reacting with the phosphoric acids are: Aliphatic alcohols, hydroxy-acids, hydroxy esters, more particularly partial esters of glycols or glycerol, i. e. esters in which not all the hydroxy groups of the glycol or glycerol have been esterified, etc. These may be from the saturated or unsaturated series. r

The derivatives of the two most common phosphoric acids can be expressed by the following in which His a radical such as alkyl, alkylene, ester such as CH3(CH2).1;COO(CH2)z-- or where a: is 0 or any small number provided there is a total of at least 10 carbon atoms in the ester radical, or an acyl radical or hydrogen, and R, is an alkyl, alkenyl, ester such as defined before, or acyl radical, and at least one of these radicals has a carbon content of 10 or more carbon atoms.

It has been found, in accordance with themvention, that the addition of one of the above mentioned derivatives to cutback asphalt will increase the adherence of the asphalt to a wet or dry surface such as is reflected in its adherence to a wet aggregate (using a standard test which will be described below) from less than'20%, up

to to It should be noted in this connection, that an increase to 80% is considered a very good result in the art. v

In preparing the compositions of the invention the phosphoric derivative need only be uniformly stirred in or otherwise mixed or may be added at the same time that the asphalt is cut-back and fiuxed with the solvent. The mixture may be warmed or heated to facilitate thorough mixture. Asphalt in the cut-back condition is compatible with the phosphoric acid compound and on thorough admixture therewith remains as a homogeneous composition. If desired, any mutual solvent or other compound inducing mutual solubility may be added.

The test used in the testing of these materials was an Ohio State stripping test for medium curing liquid asphalts: 100 grams of standard reference stone composed of 50% silica gravel and 50% crushed limestone, graded to pass a 7 sieve and to be retained on a sieve, is placed in an 8 oz. seamless ointment box and covered with distilled water. When MC-O, MC-1, MC2, or MC3 are to be tested, the water-covered ag- 'gregate is allowed to soak at room temperature for [2 hour. When MC-a or MCI- are to be tested, the water covered aggregate is placed in a constant temperature oven at 150 F; for hour. Immediately after this soaking period, the excess water is poured from the aggregate, 5 grams of the MC, heated to the temperature hereinafter specified, added to the wet aggregate, and mixed vigorously with the aggregate, using a spatula for three minutes, making sure that each aggregate particle is completely coated. MC-O, MC-l, MC-2 and MC-3 are mixed at room temperature. MC-4 and MC-5 are heated to 150 F. and applied at that temperature. After coating, the mixture is spread thinly on a glass plate and allowed to cure at laboratory temperature for one hour. The mixture is then placedin water at room temperature for half an hour, after which time it is examined and the number of particles that show stripping is determined.

Using the above test, the following results were obtained after adding to MCI-3 cutback Any of the above compounds can be used individually or in admixture.

As further showing the superiority of the invention, it was compared with the same asphalt containing 2% lecithin (a phosphorus-containing compound other than the compounds defined herein) and only 60% of the aggregate was coated, which is unacceptable.

In all of the above examples the amount of the phosphoric derivative is 2% in order to compare the results of different compounds. This amount may vary from 0.1% to more than 5%. However, asphalt is a low priced material and there is no point in using more of the phosphoric derivative than is necessary to secure the desired adherence of the asphalt to the aggregate. Generally the smallest amount will be used that will meet the particular requirements. In some cases a fraction of one percent will give a marked improvement in adherence.

In the above test the aggregate used is wet. This test is adopted because it represents extreme conditions. It will be obvious that the invention is not limited to an asphalt to be used on wet stone, since an asphalt which adheres well to wet stone will adhere even better to dry stone or any other surface to be coated with asphalt (such as wood, paper roofing material, concrete, etc). In some instances asphalt applied to a dry surface adheres well but loses its adherence in the presence of water which tends to enter the interface between the asphalt and the surface. When the asphalts of the invention are used, they have greater resistance to strippinfl from the surface under wet conditions.

It will. be understood that the formula indicated above for the additive merely illustrative and that many modifications in the radicals combined with the phosphoric acids may be made without departing from the spirit of the inven' tion.

I claim:

1. An asphalt composition consisting essentially of cutback asphalt and a phosphoric acid asphalt the materials listed below in an amount ester of an aliphatic hydroxy compound selected 0! 2% by W ig t from the group consisting of alcohols, hydroxy Per Cent Added Compound Structure Aggregate Coated Ethyl oleyl orthophosphate Oleyl-O OH 91 P CzHs-O O Mixture oi mono and dilauryl OH R-O ortho phosphate R=C12H25 l 98 RO-P=O and P=O (5H R-O H Aliphatic ester pyrophosphate, 0 i. e., where R is a diglyceridc ll radical. such as RO-P-OH R-COO-CH: R-OOO-CH2 O n or R-COO- H RLOJLOH 12-000 in so or mixtures thereof where B contains 10 to 18 carbon atoms. 93

Castor oil Phosphate (Castor o 0 reacted with about 10% P205) II where R==castor oil radical R-O-P-OH 0H linked through rlcinoleic acid 5 I hydroxy group or R-OP=0 98 n-o-l -on' on or both esters and hydroxy acids containing only carbon, hydrogen and oxygen and having 10 to 18 carbon atoms, said phosphoric acid ester having an acid hydrogen atom in the phosphoric acid radical and being in an amount to improve the adherence of the cutback asphalt to wet stone.

2. An asphalt composition consisting essentially of cutback asphalt and a phosphoric acid diester of an aliphatic hydroxy compound selected from the group consisting of alcohols, hydroxy esters and hydroxy acids containing only carbon, hydrogen and oxygen and having 10 to 18 carbon atoms and being in an amount to improve the adherence of the cutback asphalt to wet stone.

3. An asphalt composition consisting essentially of cutback asphalt and an alkyl ester of a phosphoric acid, selected from the group of of orthoand pyrophosphoric acids, said alkyl radical containing only carbon, hydrogen and oxygen and having 10 to 13 carbon atoms, and ester having an acid hydrogen atom in the phosphoric acid radical and being in an amount to improve ;'the adherence of the asphalt to wet stone.

4. An asphalt composition consisting essentially of cutback asphalt and an ester of a phosphoric acid, selected from the group of orthoand pyrophosphoric acids, and a hydroxyalkanoic acid containing only carbon, hydrogen and oxygen and having 19 to 18 carbon atoms, said ester having an acid hydrogen atom in the phosphoric acid radical and being in an amount to improve the adherence of the asphalt to wet stone.

5. An asphalt composition consisting essentially of cutback asphalt and 0.1 to of a compound of the general formula in which R is a radical selected from the group consisting of alkyl, an aliphatic alcohol radical of a hydroxy ester and an aliphatic alcohol rad* in which R is a radical selected from the group consisting of alkyl, an aliphatic alcohol radical of a hydroxy ester and an aliphatic alcohol radical of a hydroxy acid, said radicals containing only carbon, hydrogen and oxygen and having to 18 carbon atoms.

7. An asphalt composition of high wetting properties consisting essentially of cutback asphalt and about 2 by weight of ethyl oleyl orthophosphate.

8. An asphalt composition of high wetting properties consisting essentially of cutback asphalt and about 2% by weight of a lauryl orthophosphate having an acid hydrogen atom.

9. An asphalt composition of high wetting properties consisting essentially of cutback asphalt and about 2% by weight of pyrophosphate of the formula l o R.O(ll0l3 in which R is a higher fatty acid diglyceride radical, said fatty acid having 10 to 18 carbon atoms.

10. An asphalt composition consisting essentially of cut-back asphalt and a mixed diester of a phosphoric acid selected from the group consisting of orthoand pyrophosphoric acids with a hydroxy alkanoic acid alkyl ester and an alkanol, said hydroxy alkanoic acid ester and said alkanol containing only carbon, hydrogen and oxygen and having 10 to 18 carbon atoms and being in an amount to improve the adherence of cutback asphalt to wet stone.

11. An asphalt composition consisting essentially of cutback asphalt and a mixed diester of a phosphoric acid selected from the group consisting of orthoand pyrophosphoric acids with a hydroxy alkanoic acid and an alkanol, said hydroxy alkanoic acid and said alkanol containing only carbon, hydrogen and oxygen and at least one of which contains 19 to 18 carbon atoms and being in an amount to improve the adherence of cutback asphalt to wet stone.

12. An asphalt composition consisting essentially of cutback asphalt and 0.1 to 5% of a compound of the general formula:

in which R. and R are radicals selected from the group consisting of alkyl, an aliphatic alcohol radical of a hydroxy ester and an aliphatic alcohol radical of a hydroxy acid, said radicals containing only carbon, hydrogen and oxygen and having 10 to 18 carbon atoms.

13. An asphalt composition consisting essentially of cutback asphalt and 0.1 to 5% of a compound of the general formula:

in which R and R are radicals selected from the group consisting of alkyl, an aliphatic alcohol radical of a hydroxy ester and an aliphatic alcohol radical of a hydroxy acid, said radicals containing only carbon, hydrogen and oxygen and having 10 to 18 carbon-atoms.

HARLEY F. HARDMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,808,299 Benning et a1. May 11, 1937 2,191,295 Dohse et al Feb. 20, 1940 2,225,570 Pfeiffer Dec. 17, 1940 2,442,707 Olson et a1 June 1, 1948 

1. AN ASPHALT COMPOSITION CONSISITNG ESSENTIALLY OF CUTBACK ASPHALT AND A PHOSPHORIC ACID ESTER OF AN ALIPHATIC HYDROXY COMPOUND SELECTED FROM THE GROUP CONSISTING OF ALCOHOLS, HYDROXY ESTERS AND HYDROXY ACIDS CONTAINING ONLY CARBON HYDROGEN AND OXYGEN AND HAVING 10 TO 18 CARBON ATOMS, SAID PHOSPHORIC ACID ESTER HAVING AN ACID HYDROGEN ATOM IN THE PHOSPHORIC ACID RADICAL AND BEING IN AN AMOUNT TO IMPROVE THE ADHERENCE OF THE CUTBACK ASPHALT TO WET STONE. 